Vibrator of vibratory drive unit, vibratory drive unit, interchangeable lens, imaging device, and automatic stage

ABSTRACT

A vibrator including an electro-mechanical transducer and an elastic body that is fixed to the electro-mechanical transducer and that is provided with a projection, the projection having a hollow structure. The projection includes a contact portion having a first surface at a tip, the first surface being parallel to a first plane, a wall portion projecting towards an opposite side with respect to the electro-mechanical transducer, and a connection portion connecting the wall portion and the contact portion to each other. The connection portion having a spring property, and the contact portion includes a portion of which a cross-sectional area in a second plane that is parallel to the first plane increases as an increase of a distance between the portion and the first surface.

CROSS REFERENCE TO RELATED APPLICATIONS

The present application is a continuation of U.S. patent applicationSer. No. 14/515,272, filed Oct. 15, 2014, entitled “VIBRATOR OFVIBRATORY DRIVE UNIT, VIBRATORY DRIVE UNIT, INTERCHANGEABLE LENS,IMAGING DEVICE, AND AUTOMATIC STAGE”, which claims priority fromJapanese Patent Application No. 2013-215663, filed Oct. 16, 2013, thecontents of which are hereby incorporated by reference herein in theirentireties.

BACKGROUND OF THE INVENTION

Field of the Invention

The present invention relates to a vibrator of a vibratory drive unit, avibratory drive unit, an interchangeable lens, an imaging device, and anautomatic stage.

Description of the Related Art

Hitherto, as a linear ultrasonic motor that drives a driven object in alinear manner, a vibratory drive unit (a linear ultrasonic motor) suchas the one disclosed in Japanese Patent Laid-Open No. 2004-304887 hasbeen proposed.

The driving principle of such a linear ultrasonic motor will bedescribed with reference to FIGS. 5A, 5B-1, and 5B-2.

As illustrated in an external perspective view of the linear ultrasonicmotor in FIG. 5A, a linear ultrasonic motor 510 includes a vibrator 501,a driven body 506, and a pressure applying member (not shown) thatpresses the vibrator 501 against the driven body 506.

The vibrator 501 includes an electro-mechanical transducer 505, arepresentative example of which is a piezoelectric element, an elasticbody 502 that is formed in a rectangular shape and that is joined to oneside of the electro-mechanical transducer 505 in an integrated manner,and two projections 503 and 504 that are formed in a protruding mannerwith respect to the upper surface of the elastic body 502.

In the ultrasonic motor, voltages of specific frequencies are applied tothe piezoelectric element so that desired vibration modes are multiplyexcited, and by superposing the vibration modes, a driving vibration isformed.

In the motor of FIG. 5A, two bending vibration modes illustrated inFIGS. 5B-1 and 5B-2 are excited in the vibrator 501. Both of the bendingvibration modes are bending vibration modes that vibrate in theout-of-plane direction of the plate-shaped vibrator 501.

One of the vibration modes is a second-order bending vibration mode inthe longitudinal direction of the vibrator 501 (Mode-A) and the otherone of the vibration modes is a first-order bending vibration mode inthe traversal direction of the vibrator 501 (Mode-B).

The shape of the vibrator 501 is designed so that the resonantfrequencies of the two vibration modes coincide with each other orapproach each other. The projections 503 and 504 are disposed nearpositions that become nodes of the vibration in Mode-A such that, withthe vibration in Mode-A, projection end surfaces 503-1 and 504-1 eachperforms a pendulum motion with the respective node of the vibration asits fulcrum and, accordingly, reciprocates in the X direction.

Furthermore, the projections 503 and 504 are disposed near positionsthat become antinodes of the vibration in Mode-B such that, with thevibration in Mode-B, the projection end surfaces 503-1 and 504-1reciprocate in the Z direction.

By simultaneously exciting and superposing the two vibration modes(Mode-A and Mode-B) so that the vibration phase difference between thetwo vibration modes approaches ±π/2, the projection end surfaces 503-1and 504-1 each perform an ellipsoidal motion in the XZ plane. With theellipsoidal motions, the driven body 506 that has been brought intopress-contact can be driven to one direction.

Note that if the stiffness of the projections of the vibrator is high,there are cases in which an abnormal noise is generated when the motoris driven.

Furthermore, if the stiffness of the projections is too low, there arecases in which power efficiency and the like decreases.

In order to avert the above, the projections need to have an appropriatestiffness.

Accordingly, as illustrated in FIGS. 6A and 6B, Japanese PatentLaid-Open No. 2011-200051, for example, proposes a vibratory drive unitthat is provided with projections that have a spring property.

Projections 5 each include a contact portion 1 that is in contact with adriven unit 8, a spring portion 3 that has a low stiffness in thedirection of pressure applied to the vibrating body, and a standingportion 2 that connects the contact portion 1 and the spring portion 3to each other.

When force is applied to the contact portion 1 in the Z direction, thespring portion 3 that is thinner than a connection portion 4 that isconnected to an electro-mechanical transducer is elastically deformedwith the boundary between the connection portion 4 as its fulcrum;accordingly, the contact portion 1 and the standing portion 2 isdisplaced in the Z direction such that a projection with a springproperty can be configured.

Other than the above, as a vibrator that is provided with projectionsthat have a spring property, Japanese Patent Laid-Open No. 2011-234608proposes a vibratory drive unit illustrated in FIGS. 7A and 7B.

As illustrated in FIG. 7B, the projection members 29 each include acylindrical wall portion 24, a contact portion 26 that includes acontact surface 27 that comes in contact with a driven body (not shown),connection portions 21 that connect the wall portion 24 and the contactportion 26 to each other, and a fixation portion 23 that is fixed on theupper surface of an elastic body 22 by laser welding.

Since the wall portion 24 continues throughout the whole circumferenceof the projection member 29, the projection member 29 has a highstiffness in the directions defined by the XY plane; accordingly, evenif the projection member 29 receives reaction force from the driven bodyin the X direction during a driving operation, there is littledeformation. The boundary between each connection portion 21 and thecontact portion 26 is a step so that the driven body does not come intocontact with the connection portions 21. Furthermore, the thickness ofeach connection portion 21 is reduced and the width thereof is reducedby dividing the connection portions 21 into four sections with the holeportions 28; accordingly, the stiffness in the Z direction is reducedsuch that the connection portions 21 are provided with a springproperty.

FIG. 8A is a cross-sectional view illustrating half of the shape of theprojection member 29 before and after the deformation when, in thevibrator illustrated in Japanese Patent Laid-Open No. 2011-234608, apressure is applied to the contact portion 26 of the projection member29 in the negative direction of the Z-axis.

When a pressure is applied to the contact portion 26 in the negativedirection of the Z-axis, the contact portion 26 and the connectionportions 21 become deformed. Such a configuration gives the projectionmember 29 a spring property in the Z direction. If the stiffness of theprojection member 29 is high, a beating sound will be generated when theprojection member 29 is brought in contact with the driven body, andwhen the stiffness is low, even if the vibrator is not generating anyforce in the desired direction, the projection member 29 will be incontact with the slider and efficiency will be degraded.

In order to prevent generation of an abnormal noise and degradation inefficiency, the thickness and the like of each connection portion 21 areset to appropriate values.

As illustrated in FIG. 8B, in the vibrator illustrated in JapanesePatent Laid-Open No. 2011-200051, only the spring portion 3 is mainlydeformed. Accordingly, the contact portion 1 and the standing portion 2,in other words, the portion between C and D does not contribute to thespring stiffness.

Accordingly, in order to obtain an appropriate stiffness, the radius R2of the non-contact portion between the elastic body and thepiezoelectric element becomes large. As a result, the adhesion areabetween the elastic body and the piezoelectric element becomes small,and the elastic body and the piezoelectric element become susceptible topeeling and the like; accordingly, there are cases in which a desiredvibration cannot be generated.

On the other hand, in the shape illustrated in FIG. 8A, the radius R1 ofthe non-contact portion between the elastic body and the piezoelectricelement is determined by the lengths of the contact portion 26 and theconnection portion 21.

Now, since both the contact portion 26 and the connection portion 21deform, different from the shape illustrated in FIG. 8B, in the area ofthe projection constituting the non-contact portion, there is no portionthat does not contribute to reduction of the spring stiffness in the Zdirection; accordingly, the radius R1 of the non-contact portion betweenthe elastic body and the piezoelectric element can be reduced.

As a result, the adhesion area between the elastic body and thepiezoelectric element can be increased.

Furthermore, when the shape of the projection is integrally formed bypress-forming, such as by drawing, since it is easier to carry outprocessing with a larger draw radius, the shape illustrated in FIG. 8A,in which the length R1 is larger than the length between C and Dillustrated in FIG. 8B, can be processed more easily.

The projections of the vibrator and the driven body are in contact withone another intermittently. At this time, since the amplitude of eachprojection is in the order of micrometers, the contact surface of thedriven body and the contact surfaces of the projections need to besmooth surfaces in order to drive the driven body in an accurate manner.

Accordingly, the surfaces of both contact portions are finished to asmooth surface by lapping. As a result, since lapping is performed, thewall thickness of the contact portion becomes thin accordingly.

Now, in the projections illustrated in Japanese Patent Laid-Open No.2011-234608, because the contact portions are deformed as well uponapplication of pressure, the spring stiffness changes when the wallthickness of each contact portion decreases.

In order to increase mass productivity, a plurality of elastic bodiesneed to be lapped at the same time; accordingly, the following issuesare encountered.

That is, since the dimension and the warp of each piece of elastic bodyformed by press working varies, even if lapped in the same manner, theamount of lapping changes by each piece. When the lapping amount variesby each piece, the spring stiffness also varies such that ones with highstiffness and ones with low stiffness are created.

For example, when the lapping amount is small, the stiffness of theprojection becomes too high and abnormal noise will be generated duringthe driving operation and when the lapping is performed excessively, thestiffness of the projection becomes too low and there are cases in whichpower efficiency and the like decrease. The decrease in the stiffness ofthe projection also occurs when the contact portion of the projection isworn away after a long period of driving operation.

SUMMARY OF THE INVENTION

An aspect of the present invention relates to a vibrator of a vibratorydrive unit that includes an electro-mechanical transducer and an elasticbody that is fixed to the electro-mechanical transducer and that isprovided with a projection having a hollow structure, wherein theprojection includes a contact portion having a first surface at a tip,the first surface being parallel to a first plane, a wall portionprojecting towards an opposite side with respect to theelectro-mechanical transducer, and a connection portion connecting thewall portion and the contact portion to each other, the connectionportion having a spring property, and the contact portion includes aportion of which a cross-sectional area in a second plane that isparallel to the first plane increases as an increase of a distancebetween the portion and the first surface.

The disclosure of the present application includes a vibrator of avibratory drive unit, a vibratory drive unit, and either one of aninterchangeable lens, an imaging device, and an automatic stage thatincludes the vibratory drive unit that have little change in the springstiffness, that can perform a stable driving operation, and that canimprove power efficiency, even if the contact portion is worn away dueto lapping and driving of the motor.

Furthermore, in the present description, the contact surface of theprojection in contact with the driven body denotes a flat surface thatincludes minute contact points between the projection and the contactedbody and refers to a flat surface including a number of contact points.Furthermore, parallel to or orthogonal to a plane includes a state thatis completely parallel to or orthogonal to a plane, as well as a statethat is substantially parallel to or orthogonal to a plane. The termsubstantially refers that, for example, when a surface is denoted assubstantially parallel to another surface, the surfaces are in aparallel state within the range that allows the vibrator of thevibratory drive unit to exert a function sufficient for practical use.

Further features of the present invention will become apparent from thefollowing description of exemplary embodiments with reference to theattached drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1A to 1C are diagrams for describing a vibrator in which FIG. 1Ais an external perspective view of the vibrator and a driven body, FIG.1B is a cross-sectional view of a vicinity of a projection when thevibrator and the driven body are in contact with each other, and FIG. 1Cis a cross-sectional view illustrating half of a deformed projection.

FIG. 2A is a diagram illustrating a relationship between a thickness ofa contact portion of the projection and a change ratio of a springstiffness, and FIG. 2B is a diagram illustrating a relationship betweendimensions ΦA and ΦB of the contact portion and the change ratio of thespring stiffness.

FIGS. 3A and 3B illustrate shapes of the projections that are used inthe calculation of FIG. 2A, in which FIG. 3A illustrates a shape of afirst embodiment of the present invention and FIG. 3B illustrates ashape of the related art.

FIG. 4 is a diagram illustrating another example of a shape of theprojection of the vibrator.

FIGS. 5A, 5B-1, and 5B-2 are diagrams for describing the drivingprinciple of a linear ultrasonic motor, in which FIG. 5A is an externalperspective view of a linear ultrasonic motor of Japanese PatentLaid-Open No. 2004-304887 and FIGS. 5B-1 and 5B-2 are diagramsillustrating vibration modes excited in a vibrator of the linearultrasonic motor.

FIGS. 6A and 6B are diagrams for describing the configuration of avibrator of Japanese Patent Laid-Open No. 2011-200051, in which FIG. 6Ais an external perspective view of the vibrator and FIG. 6B is across-sectional view of a projection of the vibrator.

FIGS. 7A and 7B are diagrams for describing the configuration of avibrator of Japanese Patent Laid-Open No. 2011-234608, in which FIG. 7Ais an external perspective view of the vibrator and FIG. 7B is across-sectional perspective view of a projection of the vibrator.

FIGS. 8A and 8B are each a cross-sectional view illustrating half of aprojection to which pressure has been applied.

FIG. 9 is a diagram for describing an exemplary configuration of animaging device.

FIG. 10 is a diagram for describing an exemplary configuration of anautomatic stage.

DESCRIPTION OF THE EMBODIMENTS

Exemplary configurations of the vibratory drive unit according to theembodiments of the present invention will be described next withreference to the following embodiments.

First Embodiment

As a first embodiment, an exemplary configuration of a vibrator of avibratory drive unit applying the present invention will be described.The vibrator of the vibratory drive unit of the present embodimentincludes a rectangular-shaped electro-mechanical transducer and anelastic body that is fixed to the electro-mechanical transducer and thatis provided with projections with a hollow structure.

Application of an AC voltage to the electro-mechanical transducerexcites an ellipsoidal motion in the projections, and a driven body thatis in contact with the projections is relatively displaced.

FIGS. 1A and 1B are diagrams for explaining the vibrator of thevibratory drive unit of the present embodiment in which FIG. 1A is aperspective view of the vibrator and the driven body and FIG. 1B is across-sectional view of the vibrator and the driven body in the vicinityof the projection.

As illustrated in FIG. 1A, a vibrator 30 includes a piezoelectricelement 35, an elastic body 32, and two projections 38 and 39 that areprovided on the upper surface of the elastic body 32 in a projectingmanner.

The projections 38 and 39 and the elastic body 32 are integrally formedby machining, for example, by integrally forming the projections 38 and39 and the elastic body 32 from a single piece of material by work suchas press working; however, the projections 38 and 39 may be fixed on theupper surface of the elastic body 32 by, for example, laser welding.

During a driving operation, a driven body 100 and the vibrator 30 are inpress-contact with each other through the projections 38 and 39. When anAC electric field is applied to the piezoelectric element 35, twobending vibration modes are excited in the vibrator 30. In other words,the two vibration modes include a first bending mode and a secondbending mode in which nodal lines thereof are substantially orthogonalto each other. With the two vibration modes, an ellipsoidal motion isexcited in the contact surfaces (first planes) of the projections 38 and39. As a result, the driven body 100 that is in press-contact with theprojections 38 and 39 receives a frictional driving force and is driven.The driving principle of the above is similar to the driving principledescribed in the example of the related art and, thus, descriptionthereof of is omitted.

A configuration of the projections will now be described.

In the present embodiment, since the projections 38 and 39 have the sameshape, a description of the projection 39 will be given.

As illustrated in FIG. 1B, the projection 39 includes a contact portion36 that includes a contact surface 37 that is in contact with the drivenbody 100, a wall portion 34 that projects towards the opposite side withrespect to the electro-mechanical transducer, and a connection portion31 that connects the wall portion 34 and the contact portion 36 to eachother. The wall portion 34 has, for example, a cylindrical shape.

Since the wall portion 34 continues throughout the whole circumferenceof the projection 39, the projection 39 has high rigidity in thedirections defined by the XY plane; accordingly, even if the projection39 receives reaction force from the driven body in the X directionduring a driving operation, there is little deformation.

The boundary between the contact portion 36 and the connection portion31 is defined as a boundary line 101, provided for convenience ofdescription, that is parallel to the Z-axis. The portion between theconnection portion 31 and the driven body 100 is a gap so that thedriven body 100 does not come into contact with the connection portion31.

Furthermore, the thickness of the connection portion 31 has been reducedso that the stiffness of the connection portion 31 is low in the Zdirection; accordingly, the connection portion 31 is provided with aspring property.

Similarly, the contact portion 36 also has a spring property such thatthe contact portion 36 is bent and deformed when pressure is appliedthereto.

With reference to FIG. 1C that is a cross-sectional view illustratinghalf of the projection, a state of the projection after deformation willbe described.

When a pressure is applied to the contact portion 36 in the negativedirection of the Z-axis, the contact portion 36 and the connectionportion 31 are deformed with the boundary between the wall portion 34and the connection portion 31 as a fulcrum. Such a configuration givesthe projection 39 a spring property in the Z direction.

If the stiffness of the projection 39 is high, a beating sound will begenerated when the projection 39 is brought in contact with the drivenbody, and when the stiffness is low, even if the vibrator is notgenerating any force in the desired direction, the projection 39 will bein contact with the slider and efficiency will be degraded. In order toprevent generation of an abnormal noise and degradation in efficiency,the thicknesses of the contact portion 36 and the connection portion 31are set to appropriate values.

The thickness of the connection portion 31 is substantially uniform. Thecontact portion 36 has a portion in which the cross-sectional areas ofthe contact portion taken along the XY planes (second planes that areparallel to the first planes) become larger the farther away from thecontact surface side, and the contact portion includes non-uniformportions in which the thicknesses at some portions are non-uniform. Inother words, the cross-sectional shape of the contact portion in the XZplane (a plane that includes therein the driving direction of thevibrator 30 and the direction in which the projection 39 is projected,in other words, a third plane that is perpendicular to the first planes)includes a substantially trapezoid shape. A substantially trapezoidshape not only includes a trapezoid shape itself but also includes ashape that is similar to a trapezoid shape in which some of the sidesand corners are curved or rounded, for example.

The relationship between the thickness of the contact portion and thespring stiffness ratio of the contact portion 36 is illustrated in FIG.2A.

The thickness of the contact portion refers to the maximum thickness ofthe contact portion in the Z-axis direction. Lapping of the contactportion and driving of the driven body wears the contact portion and,accordingly, the thickness of the contact portion decreases. It has beenobtained by experiment that, with the type of vibratory drive unit ofthe present invention, the permissible range of reduction in the contactportion thickness due to wear is 40 μm or less.

The spring stiffness of the contact portion that has not been lapped andthat is not worn is given as 1. The spring stiffness is calculated byobtaining, by FEM analysis, the displacement amount of the contactportion along the central axis of the projection when a pressure isapplied in the Z direction.

The plots connected by the solid line are plots of the contact portionhaving a shape of the present embodiment. As illustrated in FIG. 3A, adiameter φA of the end surface 37 of the contact portion and a diameterφB of a root surface 102 that constitutes the diameter which is thelargest among the diameters, the axis of which extends in the Zdirection, of the contact portion are different. The diameter φA is 0.3mm and φB is 1.5 mm.

Meanwhile, the plots connected by the dotted line are plots of thecontact portion having a conventional shape illustrated in FIG. 3B. Thediameter φA of the contact surface 37 of the contact portion and thediameter φB of the root surface 102 that constitutes the diameter whichis the largest among the diameters, the axes of which extends in the Zdirection, of the contact portion are the same, that is, 0.9 mm. Asregards the contact portion thickness T36 of the contact portion and thethickness T31 of the connection portion 31, those of the presentembodiment and those of the conventional shape have the same dimensions.

Note that the thickness of the connection portion is a distance betweena lower surface 103 of the connection portion, which is the surface ofthe connection portion 31 on the piezoelectric element side, and theroot surface 102.

With the conventional shape, compared to a case in which the contactportion thickness T36 is 0.27 mm, in a case in which the contact portion136 becomes 0.23 mm due to lapping and wear, the spring stiffness is0.87 times stiffer: the change ratio of the spring stiffness is large.

On the other hand, with the shape of the present embodiment, even if thethickness 136 becomes 0.23 mm from 0.27 mm due to lapping and wear, thespring stiffness changes within the range of 0.995 times to 1.017 times:the change ratio of the spring stiffness is small, that is, the changeratio is 2% or lower.

This is because, in contrast with the conventional shape in which thethickness of the contact portion 36 is uniform and the contact areathereof is the same, in the case of the present embodiment, the diameterof the root surface is five times larger than the diameter of the endsurface of the contact portion and, accordingly, even if the thicknessof the contact portion 36 decreases, because the area of the contactsurface that applies pressure increases, the pressure applying force isdispersed in the diameter direction and the surface pressure becomeslow.

The above also utilizes the fact that deformation is, under the samesurface pressure, small on the outer peripheral side compared with theinner peripheral side since the distance from the fulcrum to the powerpoint in the case of the outer peripheral side is shorter than thedistance from the fulcrum to the power point in the case of the innerperipheral side.

As illustrated in FIG. 2B, with the dimension and shape of the presentembodiment, as φA/φB becomes smaller, the change ratio of the springstiffness becomes smaller, and when φA/φB becomes small to the extent towhich φA is 0.3 mm and φB is 1.5 mm, some contact portion thicknesseswill exhibit a spring stiffness ratio that is larger than 1, even if thethickness of the contact portion decreases.

It has been confirmed by experiment that, in the present embodiment, ifthe change in the spring stiffness of the projection is 10% or lower,there is almost no decrease in speed and almost no increase in powerconsumption.

The dimension of the contact portion in which the change ratio of thespring stiffness of the projection is about 10% when the thickness ofthe contact portion is decreased to a range of 40 μm or lower is, as forΦA, 0.5 mm, and as for ΦB, 1.2 mm and the diameter of the root surfaceis 2.4 times larger than the diameter of the end surface of the contactportion.

In other words, in order to set the change ratio of the spring stiffnessof the projection to 10% or under, the diameter of the root surfaceneeds to be 2 times or more with respect to the diameter of the endsurface of the contact portion.

In the actual design, the values of φA and φB are determined by, forexample, the assumed variation of the lapping amount, the assumed wearamount, and the permissible range of the change ratio of the springstiffness. An inclined portion 104 of the contact portion illustrated inFIG. 3A is not limited to a smooth surface and, for example, as in thecross sectional shape of the contact portion illustrated in FIG. 4, aninclined portion 204 may include a curved portion.

By having the above configuration, a vibrator of a vibratory drive unitwhich has little change in its spring stiffness can be obtained even ifthe contact portion is worn away by lapping and by driving of the motor.Furthermore, a vibrator of a vibratory drive unit or a vibratory driveunit that is capable of performing stable driving operations can beobtained. Still further, power efficiency of the vibrator of thevibratory drive unit or the vibratory drive unit can be improved.

Second Embodiment

In the second embodiment, as an application example of the vibratorydrive unit of the present invention, an example in which a vibratorydrive unit that is built in a lens barrel of an imaging device (anoptical apparatus), such as a camera, and that drives a lens (an imagingelement) for autofocusing will be described with reference to FIG. 9.

FIG. 9 is a diagram for describing a drive mechanism unit of the lens ofthe lens barrel.

The drive mechanism of the driven body according to the vibratory driveunit of the present embodiment includes the vibratory drive unit (thevibrator and the driven body) of the first embodiment, and a first guidebar and a second guide bar that are provided parallel to each other andthat slidably hold the driven body.

Relative displacement force is generated between the vibrator and thesecond guide bar that is in contact with the projections of the elasticbody by an ellipsoidal motion of the projections of the vibrator that isgenerated by application of a drive voltage to an electro-mechanicaltransducer. The above configuration allows the driven body to bedisplaced along the first and second guide bars.

Specifically, as illustrated in FIG. 9, a drive mechanism 100 of thedriven body that employs the vibratory drive unit of the presentembodiment mainly includes a lens holder 52 that is a lens holdingmember, a lens 57, a vibrator 1 on which a flexible printed board isbonded, a pressure applying magnet 55, two guide bars 53 and 54, and amain body (not shown).

The two ends of each of a first guide bar 53 and a second guide bar 54constituted by two guide bars are held by and fixed to the main body(not shown) so that the first guide bar 53 and the second guide bar 54are disposed parallel to each other.

The lens holder 52 includes a cylindrical holder portion 52 a, a holdingportion 52 b that holds and fixes the vibrator 1 and the pressureapplying magnet 55, a first guide portion 52 c that is fitted with thefirst guide bar 53 so as to function as a guide.

The pressure applying magnet 55 that is configured as a pressureapplying unit includes a permanent magnet and two yokes that aredisposed at the two sides of the permanent magnet. A magnetic circuit isformed between the pressure applying magnet 55 and the guide bar 54 suchthat attractive force is generated between the two components. A spaceis provided between the pressure applying magnet 55 and the guide bar54. The guide bar 54 is disposed so as to be in contact with thevibrator 1. Pressure applying force is created between the guide bar 54and the vibrator 1 with the attractive force described above.

Two projections provided on the elastic body are in press-contact withthe second guide bar 54 such that a second guide portion is formed. Thesecond guide portion utilizes the attractive force of magnetism to forma guide mechanism. Although there are cases in which the vibrator 1 andthe guide bar 54 are separated from each other due to reception ofexternal force, the above is dealt with by the following measure. Thatis, a measure is employed so that the lens holder 52 is returned to itsdesired position upon a fall prevention unit 52 d that is provided inthe lens holder 52 hitting the guide bar.

By providing a desirable electric signal to the vibrator 1, a drivingforce is generated between the vibrator 1 and the guide bar 54, and withthis driving force, driving of the lens holder is performed.

In the present embodiment, although an example of a pressure applyingmechanism employing a magnet has been described, the pressure applyingmechanism may be a spring, and the configuration may be such thatpressure is applied to the vibrator 1 and the second guide bar 54 by theforce of the spring.

Furthermore, although an example has been described in which the drivingdirection of the vibratory drive unit and the displacement direction ofthe lens are parallel to each other, the present invention is notlimited to the above example. For example, a plurality of vibratorvibrating drive unit of the present invention may be employed to rotatean annular member and a torque thereof may be converted into andretrieved as force in the displacement direction of the lens so that thelens is displaced.

In the present embodiment, although an example has been described inwhich the vibratory drive unit is used to drive an autofocusing lens ofan imaging device, the application example of the present invention isnot limited to the above example. For example, the vibratory drive unitmay be used to drive a lens holder for displacing a zoom lens.

Accordingly, the vibratory drive unit of the claimed invention may be,in addition to the imaging device for driving the lens, mounted in aninterchangeable lens as well. Furthermore, the vibratory drive unit maybe used to drive an imaging element and may be used to drive a lens andan imaging element during a shake correction.

Accordingly, an interchangeable lens and an imaging device that arecapable of performing stable driving operations can be obtained, orpower efficiency of an interchangeable lens or an imaging device can beimproved.

Third Embodiment

As a third embodiment, an exemplary configuration of an automatic stageapplying the vibratory drive unit of the present invention will bedescribed with reference to FIG. 10.

In the second embodiment, an example of an imaging device has beenillustrated; however, the application is not limited to the imagingdevice and may be used to drive various automatic stages of a microscopeand the like. For example, the vibratory drive unit can be applied todrive a stage of a microscope and the like.

FIG. 10 is a perspective view of a microscope illustrating the presentembodiment.

The microscope of FIG. 10 includes an imaging unit 60 that is built inwith an imaging element and an optical system, and automatic stage 61including a stage 62 that is provided on a base and that is displaced bythe vibratory drive unit.

An object to be observed is placed on the state 62 and an enlarged imageis taken by the imaging unit 60. When the area of observation extends ina large area, the stage 62 is displaced by the vibratory drive unit suchthat the object to be observed is moved in the X direction and the Ydirection of FIG. 10 such that a number of photographed images areobtained.

The photographed images can be joined together on the computer (notshown) to obtain a single image that has a high resolution and in whichthe area of observation is wide.

Accordingly, an automatic stage that is capable of performing stabledriving operations can be obtained, or power efficiency of the automaticstage can be improved.

While the present invention has been described with reference toexemplary embodiments, it is to be understood that the invention is notlimited to the disclosed exemplary embodiments. The scope of thefollowing claims is to be accorded the broadest interpretation so as toencompass all such modifications and equivalent structures andfunctions.

What is claimed is:
 1. A vibrator, comprising: an electro-mechanicaltransducer; and an elastic body, wherein the elastic body is providedwith a projection protruding at a side opposite to a side at which theelectro-mechanical transducer is provided, and a contact portion thatprotrudes along a direction in which the projection protrudes isprovided to the projection, and wherein a width of a base of the contactportion is larger than a width of a top of the contact portion.
 2. Avibratory drive unit, comprising: the vibrator according to claim 1; anda movable member, wherein the movable member is configured to contactthe contact portion.
 3. An electronic device comprising the vibratorydrive unit according to claim 2.